boiler in winter

We are mainly going to use our motor home for day trips until around February half term and were not planning to fill it with water for each day trip but leave the tank empty. I thought this would be easier as it is in a storage place and we can just drive in and drive off. However, it has only occurred to me that the boiler has an automatic thing on it (technical term, I know) which dumps the water in it when the temperature gets low. I presume the last couple of days would be low enough for this to happen?? So presumably the next time the boiler needs to go on it will need water. Will we be better putting some water in the tank for each day visit then? I am not sure what would happen to the boiler if we accidentally put it on and there was no water in it. I'd be grateful for any advice - had no idea there were so many things to think about!

We have a Truma 4e combi boiler. It runs without water in it. We also have a dump valve ( operates at about 3 degrees C).
The problem is, if the temperature is below 3 when you try and fill the system with water, the dump valve won't close till the temperature around it rises to above 3.
So, we had a preheater fitted on the valve that raises the temperature so we can fill the system in cold weather.
That all sounds good, but we never empty the water out and keep the heater on low when it's cold, which keeps the valve warm. Obviously, we use the van all the year round and the water us replenished regularly.

We have to keep ours in storage so just worrying about not being able to get to the van for perhaps a week at a time. We intend to use it for days out in the winter and some weekends when time allows. Our first extended trip will be February half term.
If you are in the van and the temperature outside drops, presumably the dump valve won't operate if you keep the van warm??

Our first extended trip will be February half term.
If you are in the van and the temperature outside drops, presumably the dump valve won't operate if you keep the van warm??

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Correct!
If it is very cold and we have a hook-up, we run an electric frost-watcher heater overnight to keep the chill off. On sites without hook-up, we have left the Truma running all day and night on tick-over when the outside temperature has been well below zero. Amazing how fast the gas goes though: we have used an 11kg bottle in a weekend.

We have a manual dump on our boiler, which requires me to flick a switch to drop the water. The coldest weekend so far, we were actually using the van, so no problem.
Last year when I saw that cold weather was on the way, I would do the following:
Dump the boiler,
Dump the fresh
Open all taps, and leave the shower head on the floor
Open the grey waste tap

It did mean that when we came to use it, I had to re-fill the fresh tank, but a small price to pay I felt. It is worth remembering that the taps are open. The number of times I switched the water pump back on and had water spraying around the van was incredible!

As it really only takes a few minutes to refill the fresh water tank, I am in favour of the complete dumping of any water for if things can go wrong, like a power cut on the coldest day preventing using an electric heater, they will. I have also found that leaving the system primed for an extended period, the water begins to develop a bad taste. For this reason I totally drain the system, ending with an airline attached to the shower hose to clear out any remaining drops.
Alan

As it really only takes a few minutes to refill the fresh water tank, I am in favour of the complete dumping of any water for if things can go wrong, like a power cut on the coldest day preventing using an electric heater, they will. I have also found that leaving the system primed for an extended period, the water begins to develop a bad taste. For this reason I totally drain the system, ending with an airline attached to the shower hose to clear out any remaining drops.
Alan

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We never drink the van water so taste isn't an issue. We don't drain down over winter as we use the van

Border Collie rule No 1 : If it looks like it might be mine, I think its mine or someone else thinks it might be mine.. or if none of the above apply.. its mine! @archiethedug

We drain the van down in the winter, We are going away for one night, site has toilet and showers, so will take a 5L container of water with us, for tea making, washing hands and flushing the loo. We fill the tank when going away for longer periods though and drain down before leaving the site. Always carry some drinking water with us though.

Hi Lizi - As you are only going to use for odd days or trips - perhaps to give yourself an easy life - Drain everything down now. Carry water in a couple of containers.
Use onboard tanks in spring when you start using again.
Your boiler should be fine running the heater without water - just check in manual-but can,t see why there would be a problem?
Simples